SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50df8682c2d54eaba115894dd07ada87d03c4a4309475fe0c7f68a8ba87b78b4' 
  AND token = 'vcr/PgCQgHr8fuWBcdjZAUDm5WKVJV7VSxr0EfPxAkE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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