SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57a4b3ddaa39c4dde4be850544fcebb432193c42562748b6ecef8070f7aa7534' 
  AND token = 'nnzwguoHwOYRlQ1FVb70JnT+MbmZ1BzwFO7t5/n9dqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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