SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2d7c38dd58d7bce89bf0c9d88c78df19bdba97a1d64fb14bcade1177f1998f5' 
  AND token = 'HXastdkbfSSgdYn8FkrCSuJK8YuhT9PtOtTDcjhPJuk=' 
  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"
    }
  }
}