SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55bdb7a1569ec9af367475e95f33688f9779da919435cb9556311c6e784a3ec7' 
  AND token = 'kvIXc9m++rs9OUZd2asW/HMGnWtzz1fxco0u8lyqxEU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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