SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fdd9013dc2feba46377e556ca6cdfdce8393323795128143751546b06f96d9de' 
  AND token = 'K8PCPBrTYqBxL++hmxqX1y4EadOUfaYSZngQHR4daMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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