SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f767b2c632b9d5954348d49c69c9e268b4beea4aca4a22b66a564df04ebaae65' 
  AND token = 'NDxSQvrxmP9cNYdSwPH//+OfyZWvldDThgEbAfdTyZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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