SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0db74b0373a1687286f4a0e9b6dad9a988e089ddb5384f005ffa8a0185e53f6' 
  AND token = '1/Xu6nyDcLFci0U95w0lRgBCftugG6aoiMauJmWyM8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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