SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ec5a586470423af7bbcfa1f535934fb6b4583e92108f15e6d640d58ed5ad435' 
  AND token = 'oCs7z6KayYNONJx329mglBk4kT3vNEnLDlV41fOCTTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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