SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2e4cd5d51fd2fc8cf804dde842a6663754667e3813856219cfeba627628d1c6' 
  AND token = 'Rr+2COqYEhx+/T2tKtTbUDK5Eje5NB9UUKyinHG8dXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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