SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c351368607b38b5a14dfb3bbbc2543569c098dd04fb3d8a1848ab379922ec660' 
  AND token = 'm+azB3WJXzK9FQcizZsvX7saKPcoUGJSItbCQX/M+6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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