SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b15dd6195b0ef8491062bee76d4f70751741d470f851984e797ec8f6f4bdf3d' 
  AND token = '22HjYvueWCXO941pvMehpPsl0tUErLHOnRrFhsk8qnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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