SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b7d48a480f5344967f658b92cc38eb96b0abb2b579251cc37e90264292cdf8d6' 
  AND token = 'b9o/9h1/1UE3W7jxXZ9XNlkr1hLHG+u3fk360yZocCI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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