SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0c8ad99bdfffa435352948a6f50c837b1911628627e2cefb6345e1c0ea69840' 
  AND token = 'AyKIwAm0v9pQpSiYIk7pCU1YLOTYyY9zjPhPfVw48V8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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