SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98f147aef10d2d066aa925b41f6b5570df8076e2a40b24118b4df710c3c2b701' 
  AND token = 'z8usJi4WRXdMdjeFOtTjIRUyaQVx7drcKp6z7GQwx74=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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