SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d92ae02f3d498731d47671b49203988842b6ee3676aaaa87a6aae25847bd6e9' 
  AND token = '4w8JaXpYBVgT9mFE7SDzemwtX98YPNxqzL1oLras5hY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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