SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3a9b604fe79758fd3c822340ba518aabea68304c8db626f4fb6767db14036ba' 
  AND token = 'EJEBlcFtOk2Y3jteN3zys0e5dK2uUYDm/hAJWj26m/I=' 
  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"
    }
  }
}