SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8fbb78eef1c24684bd5d2693fe5d8ddc6c85b99e3d0efb8e1f7f56d2574c423' 
  AND token = 'P+8DgnERwlQOYAjJwHWmWKWSMeyOfOhgu+vsnREn/nE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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