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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef29538aa9c12ce3ca34a6c216925a11c6964534e67411b8d62ab1c65dcd3f4a' 
  AND token = '15Nf3mxx2GtQL/aOBzoTLc8pP7NFkfrNxGm//GfSy7k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}