SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '834212d1310a416dcc0c7b97bc326ac0eb37bc8f318c2618295339a5f5b20c04' 
  AND token = 'DXTSMS/HHBRGkok4dNdPIy6GlOF76hT6kmr7sBsBty0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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