SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9f16135b625693f4d371c8acba37fe9d8566770cd9887ce3fe61ee8b197e2e4' 
  AND token = 'PbcClwykQ6egQ2+WrS40ywBQFgtgCXZHDAvXHHOXu1o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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