SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e2b3d7667fbc347528e5197e84df9019da5c167f140d83121f2e2a8bac49afe' 
  AND token = 'aH0TRP5RnlUP2KiuzYAeXDycYsLdt4SNjcrx0etUnbs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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