SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48e7135eb03a7949e5457a128ee0c0224fa216387e73b3d26e8f9631bf78b410' 
  AND token = 'caUO8PIKxVOP6cWarlbMqEC4hGSxvOyMrsIV0Se+ctM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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