SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '578a0b1a2ddd55c15db660587a4b3112b3930a594ecbe527072deab45f19790e' 
  AND token = 'ImlLGiL+n3ehb/LRlYyeq3zoBh5swUYBviPJQanpU1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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