SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1f6d3d2fa295d993978f5da3711f22cda589a084047ae84ed3b3a3297761686' 
  AND token = '6UVDgSnbuC9SJ+sxsPt2t09EG7UNwGjOwLh42UBLUKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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