SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba927f0ded7e929edffe7d1937601ac6b3572f2f035e5d143394a8083f28708e' 
  AND token = 'PvCChEQPnDs/gL0XFJ81QcxEt6ggWj1VKILP5fVE/pk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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