SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '1c421ed60da351cfd8017a9fef7ef959fc154017256e25756e78c150e3cfded1' 
  AND token = 'RltQjnBlJE9XTyKvvwv76b9j9exfF5+bb08wudl7Bv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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