SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b9b3acf41942db09f83978ad621e34c26cf10e40b86466665d9286f7051d770' 
  AND token = '6iyDPytIzcu6sk9qO7+IGqYtlJMOXvoaVxk8LeqUzt0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}