SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a41a66a128f060ca263e5cbdafbf7ea17ccf37902ebe82f40a60222257aea446' 
  AND token = 'doKRrV3sg4vgiEJ7A0UVtMg99enJK6ienY/lSSzskjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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