SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c0c36b8032872be3ca3070626b87ab5d41fa1173f7e7c9dfc7c6d5114a77b12' 
  AND token = '5keXdMYnq4uQgHp+okxaBQItqOWvjrBLYMrmog4rPUo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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