SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c251027e1f8a64477b45355c9a5cd28c46433bcc181872a21345a012a91ebe2' 
  AND token = 'i9MNLwWc5q6JjtZLX84/z7eybOt9byFqmK/v4Pn/ilc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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