SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e556ddacfe3f240909c8444bf29e06a00b419a32ee8f704d689737a220928c0' 
  AND token = 'xPK3FgqREOA28T0QXpySadaEoQuIhdbQAOz1VSVdYtw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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