SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '427445d66fa69b2f1784831567f449f3fec54ddaa864c0198e6bfda07b8da823' 
  AND token = '8hN32YNM/itrjHQbi8szgiFQF71IlSi+pRkx/AGnZwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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