SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '99f8edc7b85712843d6f585a22d1c7dd2ec57228bd6059f9e79ee78c01f48239' 
  AND token = 'PlBZuBP+ByRU485O9GQAF+GKe2uITGVjBcNyw6gmHkE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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