SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4e7d5254abc5fc8791d1ac688286bf2c6a03b0a3669cee553a4de13fadda763f' 
  AND token = 'bYU3vPDAUI8zii6W3bqu21E3QluZGySwUCGNkOIZUFo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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