SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54975e34e229a604b4c383c4f674ef3442316922f9a9a9ddf57bc403f340cfb6' 
  AND token = 'bUnULeELdxR8QYmuO5E68itsb7hGhfLagNXa5l91oSU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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