SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83c6ebdee9d7e0b195ac37906447c1df96d3531318affea43f45658963755109' 
  AND token = 'msxQ3c8Uro4gEIVb7n8TALziV53CmkRBDiiZnln6X/o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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