SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68791781cc41d9af3c2610252752a75ea55349d43bfe0b58e04df3e7ca41c513' 
  AND token = 'PlIcz9qTbCCDV+o8hFzp6RUMtz+6WLJB5+LCVAzb0jY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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