SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ffc6a085b67277f7def791159642eb2cc212c366ab6b957c57da38855079408' 
  AND token = 'F9NSfEMnq7uP+9VHG46pLCnuJK/ZOKVTwpmJLbVjhGM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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