SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b3bc55815fa388bcc7238795489d35ab0621f678587aa978d1d5da0a88ac940a' 
  AND token = 'XkMbSo6H5+kinpHjsamBCsg3ZYXjfAzO2zLFrgHjhFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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