SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6c0180cb5987227eb3ba429ff5da7ccaf149860627a58fbd352417b9e585502' 
  AND token = '6j0ZWQZhAaHmRoknbPdPJksUkJ4yKVtd6BuwqX3PU9c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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