SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af51ce87489670683d08d116fed10be9a88a39cc720c48545a84d055c970385c' 
  AND token = 'YEhLbvSXveEqXXp9mPY1Jf4Wxml6U/bMLT2L/o7mZtE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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