SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5dfdcbf1af36e79bd890281de20cb8f04bcb736120d1b99c4686699906e6216' 
  AND token = 'to0JHP/HgUn4hHcwuLOSPLZWtAfuxtfRGVR6ILSVrv8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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