SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a0d53346b7b354821e63336afce1babef8f8071036eb2a9055462f5dd8f5e9de' 
  AND token = 'gMrGOMK/kyE+/Avy19nYGqR9L0zaN6b26ZLhvvNc/Ho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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