SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38574fcce799957b01bacd9563133dd3b5386d9f0e745345103e8cbaa0622ed3' 
  AND token = 'j27GyLcB9DqBYFb3W5wvmK/PDZh/BN+RZlmQiZ5siMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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