SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3d1037605e3d8ea38b4fd4550923113b67139897197290073f22960ab528e8b' 
  AND token = 'Nu0sfuY5B4V7JPCoklWQ5Bdpc1UW2u6bio0MTQhd5ww=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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