SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f9f992ee93290cb1efd3c9b1006541399efb5de8302250188079af6f522c205' 
  AND token = 'moeNrP7cYbp6+8swN0dw0scLedTTuud1RBEgMLhqUxA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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