SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe13162daf2d1be71816d0b6d1ad8024889734d765dded9b8954eaf016e9aa9b' 
  AND token = 'oFAJAEiZGcYPglD8QL7pgNguET69pUXGj/s8CoNesmY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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