SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a4831c09d93e400c0fcd623e1ca94b6a0de768353dc9cad4011b500dc329cf62' 
  AND token = 'Liot/F2tUE9j3WFhEWlWyoFJB9td007Cp4AVV+trT30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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