SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fa40979b74ec49e57bf3cc62c603608d37d6779013914b70c8793afd1d866179' 
  AND token = '8GdVqDvL3Y92s79sy5TnoaD9NN/L/CmqdJkRxA9kZ/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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