SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fcdca62f439970f6855471b970e6225808a331b07f158e9cd35b675c45c0f48' 
  AND token = 'mNfu27ZBXtkVAF/6oRdMmLr/liEvq5wjV/cpQEXbS/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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