SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99c85c766ccdb9977d686632a65857a668f2dad8500f20206469cab461b38d04' 
  AND token = 'oL7CEkV+WkQlJoSSnIQoJdyaqOPYMSFfvLUsvq+NyJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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