SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81dfb466c9576f5efee7029477030900402f63419e0e5a449b83415ad32930ed' 
  AND token = 'yEWAEcInCvlD4fBoih8R4XUrPfv0PI8bUBzwPPYzOr4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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