SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e83edaff9327abbe3047632233c08ec79eb46b81146846f827a239e0e8e4b91f' 
  AND token = '23pVaMmSTKoQzbtSXB7nFoA4Slc17Cus9BT9Dt3GtIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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