SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a75f28574069fc184626749908636d09147927eac0c0db5fa5e06662c57d49a' 
  AND token = 'a57TIF0JbIO7bR7ALYPM1RV3jvVUcRfFFvNk1TKF6t4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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