SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '293b2afa086f22e09c7c5d63886c23080994ff68619da22ba4f014ae2877f978' 
  AND token = 'MudW80whZaFoQdQBJBJGSG0JykC3bGkcTFPdaWOdVwM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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