SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ee2628a6c461c047e7bf54c4017fd0f87955674d52c48bfb54891d8c768df23' 
  AND token = 'BC2D0swmbPMmtIBbk+TOU/9h1VUhcXuCsJu5ZoOtL8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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