SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f89fe9cddb395d767c7206e953be802bdccc1728968f65e547c03acea59a309c' 
  AND token = 'NN6ubfBJtI3XtPoe/KUBq9ddca8VbYTv6OTDwZlWLQU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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