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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f791cda850a81d13956b4b102ba7c8675340cee6b65270f81b11b54d8c9c46c9' 
  AND token = '6YsrIgkbjyO1ru40BlS9q3uLDjbG0DlXB3CTrXzpj1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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