SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'feb4291850608ef0102ef6d75c6ca0f8b79524768f4c016aa636b5934b6d8b65' 
  AND token = '7ieRki5xSgcjuZLSE4jqcgjpsxFmW7smgF0iyqi9cWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}