SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75f1c7f0b251e6cd26812c61de4ee47bd536cd68d7d6c1d37a6d622487b834dd' 
  AND token = '6qD8n21vJyodko4zgzW5Bs3AU6ulrFtagRoCV83vAUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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