SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bae014527e0fa3df990519292599fcf2f1c52c634be5a3bf34944d57e9812352' 
  AND token = 'UV9kiqMyBFeTHWIUejZIte7Fr7w91n7OLNfrFRm0/dg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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