SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8088d05405fbc8e0eb84c0d9d28085550988c08266646537ffefac614c074a2' 
  AND token = 'DRbjWG11OnYTHBzNLJY01r6Ol4qGZhS/loBcsyfktm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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