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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '701a1a7d77fb2d0fc8ce60e994ac1feb16d48d164d12e03739ef73babe7142f7' 
  AND token = 'vscJBN6XPd2fwZHEXMQlCVlQ6OVEh1PsYvdUub+Fkr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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