SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da3d40a64fd3892aa690f67a54fde253d114291ee6c3a359a289687016c9477f' 
  AND token = 'T6sMyPVLbr/P6+H5J+AQVTolYi207nwrjBU4v+f7Qgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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