SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81ceca068c244d6801566ac4a5db98f92828e753156d32a83331434f986d4ffa' 
  AND token = '6CdYF4fdIk/OML3vCLbFW/qhCfKICBKdbzuzoJi+OKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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