SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84c1815329b24417ced5817bb7ff26d05413e8d571ed23b4c6609baa75114464' 
  AND token = 'i2aMrtm5AjNCFP32SFEMVEUlnBh68LVd5udedMHkvFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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