SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5847ccaf8353583f58710d2347aeeaf2605dba429e3b311f2f5fac0849a7765e' 
  AND token = '9hfLCAw9XDig31bDhuiiWhrjhetE1Ncs8ticUrGHEVs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00073

JSON explain

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