SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c355539ac055431607592a3a8e4408f756edaed2552470dfecf6a6cae6a7aeaa' 
  AND token = 'Wuj/fPmAk4JiHKmAGr7DW/JChTapiKfIZSrPftiszJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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